The subject matter disclosed herein relates to a system for providing cooling and purging air flow to a rotary machine online monitoring system.
Certain gas turbine engines include a turbine having inspection ports configured to facilitate monitoring of various components within the turbine. For example, a pyrometry system may be in optical communication with an interior of the turbine via the inspection ports and configured to measure the temperature of certain components within a hot gas path of the turbine. Typical pyrometry systems include a sight tube inserted within the inspection port and configured to covey emitted and/or reflected radiation from turbine components to a detector. Such pyrometry systems utilize a transparent window positioned at the tip of the sight tube to protect the sensitive optical component of the sight tube from the hot gas stream flowing through the turbine. Unfortunately, during operation of the turbine, the window may become obscured due to buildup of contaminants (e.g., unburned hydrocarbons in combustion products and/or particles from an air flow) on the surface of the window. In addition, molten metal particles may become imbedded within the window upon impact. As the window becomes obscured, the accuracy of the pyrometry system may be reduced.